


You're Mine

by KaitlynSpeight



Category: Supernatural
Genre: Ace Castiel, Alpha Dean Winchester, First Kiss, I Don't Even Know, M/M, Mating Cycles/In Heat, Non-Traditional Alpha/Beta/Omega Dynamics, Omega Castiel, Omega Sam Winchester, Soul Bond, a/b/o dynamics
Language: English
Status: Completed
Published: 2016-04-20
Updated: 2016-04-20
Packaged: 2018-06-03 10:44:20
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,003
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6607756
Author URL: https://archiveofourown.org/users/KaitlynSpeight/pseuds/KaitlynSpeight
Summary: <blockquote class="userstuff">
              <p>Cas has always been repulsed by alphas, so why is he falling ass over elbows for Dean before he even knows him</p>
            </blockquote>





	You're Mine

**Author's Note:**

  * For [SammySammyDean](https://archiveofourown.org/users/SammySammyDean/gifts).



> My first and hopefully last foray into A/B/O dynamics, hopefully I didn't butcher it too bad:)

It was late, a young omega shouldn't be out alone, Castiel knew that.. Buuut he couldn't sleep, and honestly what was any creep going to do to make his life any worse than it already is? He’s being forced into an arranged mating with a partner he doesn't love, who would in turn force him into the mating bed. 

 

He half  _ expected _ to be raped or killed, he just didn’t care. What he  _ didn't _ expect was to run head first into an alpha who came barreling at him from a side street. Or to then have his hand grabbed onto by said alpha, and be dragged back the way he came.

 

“what the fuck?! Let me go!” Cas yelped, but the dude just tightened his grip. “Sorry sorry sorry just come with me.” He babbled, dragging a stumbling Cas behind him. The finally came to stop out on the main road, where the alpha doubled over panting and Castiel slowly backed away. 

 

“I’m so sorry, there was…” The alpha peeked up at Cas, eyes wide and chest heaving, “group of alpha’s, bad news, they were after me, woulda found you, couldn’t let…” He wheezed, coughing weakly, flopping onto the ground and trying to catch his breath. Cas froze, the alpha was trying to...protect him? 

 

“Thank...you, here, let’s get you out of the road.” Cas hauled the man to his feet, helping him hobble to a bench just down the street. “Thank you, the name’s Dean, if you wanted to know.” The alpha - Dean - mumbled, sitting down heavily. “Castiel,” Cas said, sitting next to him and tucking his knees to his chest. 

 

“What are you doing out this time of night, Cas?” Dean asked, smirking at the smaller boy, and Cas shrugged, “looking for an alpha to sweep me off my feet... Literally.” He teased, and Dean blushed, rubbing the back of his neck, “sorry, really. I couldn’t sleep, so I went for a walk, apparently I wandered onto some gang territory and pissed them off. When I saw you I… couldn’t let you do the same thing.”

 

Cas shrugged, leaning back on the bench, “I couldn’t sleep either, Balthazar warned me not to come out but… I just didn’t care.” Dean raised an eyebrow, “well that sounds like a story, wanna talk about it?” Castiel made a face, leaning forward and pulling his knees tighter against him, “no offence but I don’t know you.”

 

“No one’s easier to talk to than a total stranger, and you know it.” Dean quipped, turning to face Castiel, and Cas sighed. Well, he  _ did  _ want someone to talk to, and Dean was right, he would probably never see this alpha again after tonight anyway. “Balthazar is my mate… Well, he’s going to be.”

 

Castiel sighed, might as well tell him everything, “see, I’m… I don’t want to be knotted, it just… Grosses me out. Just thinking about,” he shudders, sighing miserably before continuing, “so my parents decided the only way I’d get a mate was if they forced me into it. Wait till I go into my next heat and let Balthazar take advantage. I was half hoping someone would…  _ would  _ hurt me if I came out here tonight, so they would at least have to wait. 

  
  


“I don’t love Balthazar, don’t even think I like him and I don’t… If I’m gonna be forced into bed with someone I want it to be someone I… Someone I can at least look at and not hate at the end of the day. But my stupid biology and… My heat starts this week. And by the end of it I’ll be stuck with the bastard…” 

 

Dean pulled a face, “why-” he cut himself off, biting his lip, “don’t you have somewhere else you can go this week? Put it off for a while longer?” Cas shook his head, looking down, “my family wants it, and I don’t really have any friends, I mean… Who would wanna be friends with an omega that doesn’t put out, I’m a freak.” Cas shrugged, and Dean flinched. 

 

He couldn’t place why he wanted to protect this omega, like Cas said, they didn’t know each other, but he couldn’t stand the idea of him getting hurt. “Look, uh… My little brother’s an omega, he’s ah, due for his heat soon. I usually fuck off for the week and let him work it out locked in his room, if you… wanted to whole up in my room for… Erm…” 

 

Castiel raised an eyebrow at the larger man, “you’d open your room to a stranger? While your little brother is alone? In heat?” Dean flinched, rubbing the back of his neck, “well when you put it like  _ that. _ I don’t know, man, I just... Can’t stand the thought of you being forced into something like this…”

 

Castiel looked away, chewing on his lip. “Well, I… I don’t want to intrude, but I really don’t see any other choice, if you  _ really  _ don’t mind… I would really appreciate that.” Dean shook his head, smiling at the smaller boy, “I don’t, anyway, I’ll know if something happens to Sammy, and now I know your scent, so don’t think I won’t track you down and destroy you.”

 

Dean smiled, enough so his fangs flashed in the moonlight, and Castiel cringed. “Honestly I’d prefer you kill me here than go home...” Dean sighed, “how about we go to your place, you can get some stuff. I’ll stay outside but if he tries to hurt you…” Castiel nods and stands up, offering Dean a hand. “Thank you.”

 

Dean shrugs, taking Cas’ hand up and following him towards his apartment building, “so, why do you hate this guy so much anyway?” Dean asked as they walked, not moving to drop Castiel’s hand. It felt too small in his, fragile, and he was met with an overwhelming need to protect this man. 

 

Cas hesitates, Dean seems nice, but he doesn’t want to push him, he isn’t sure how Dean would react if he told him the truth. “I’m not entirely sure. I think it’s… That he’s okay taking advantage of me. He knows I don’t want his knot, but… He’s gonna fuck me when I’m in heat, when it's my biology, not me, and he’s okay with that.” 

 

Dean cringed, squeezing Castiel’s hand. “That’s kinda fucked, you’re right.” Cas just shrugged, stopping outside a large building, “this is me, I’ll be out in a minute.” Dean nods, reluctantly letting go of Cas’ hand and flopping down on the steps. 

 

This was a mistake. He doesn’t know this omega, he shouldn’t be letting him move into his home, especially not when Sammy’s vulnerable. But there’s just something about him… Something in Dean  _ can’t  _ let this omega get hurt. He just wants to see him smile, those gorgeous blue eyes light up, he shouldn’t have to look like he’s on death row. 

 

A loud shout pulls him from his thoughts and he looks up at the building in confusion. “You’re gonna run off with some alpha you don’t even know?! Are you that stupid, Castiel? Can’t wait to run off and get raped by some creep?!” Dean growled, how dare this man insult his… his what? Friend? Were they friends? They just met.

 

“More like I just hate  _ you  _ that much! I don’t care if he  _ does  _ rape me, at least I won’t be stuck with you!” Dean simultaneously puffed up with pride and curled in on himself with remorse at the bold bold words, Cas shouldn’t have- his thoughts are cut off by the sound of a harsh smack tearing through the night. 

 

He can’t remember climbing the stairs, or how he got the door open, but the next thing he knows he has the other alpha pinned to the wall by his throat, and Castiel is behind him sobbing. Slowly, the omega’s voice cuts through the red haze clouding his vision, “Dean, Dean let him go. I’m okay, don’t kill him. Please don’t kill him.” 

 

Dean snarled, baring his fangs for another moment before backing off. “Go get your stuff, Cas.” He ordered, not taking his eyes off Balthazar. Cas ran out of the room, coming back a minute later with a bag slung over his shoulder.

 

“Dean, come on, let’s go.” He whispered, tugging on Dean’s arm, and the alpha finally turned to look at him, growling at the bruise that was already forming under his eye. 

 

“Are you sure you don’t want me to kill ‘im?” He cast a glance at the cowering alpha before him, fucking weak, he wouldn’t be able to protect Cas. Wasn’t any good for his omega, not worthy.

 

“I don’t want you to get in trouble. Dean, please.” Dean huffed, but turned to face Cas, taking his hand again.  _ He _ could protect Cas, he would never hurt him. Cas was  _ his _ .

 

“He’s broken you know,” Balthazar called as they got to the door, and Dean felt Cas tense beside him. “Won’t let you knot him, strong little fucker, fight you off, too. I’ve had to go to work with a black eye more than once.” Dean snarled, and Castiel tugged his hand, “come on, Dean, please let’s just go.”

 

Dean takes a deep breath and let’s Cas drag them out of the apartment. “He tried to  _ rape  _ you?” He whispered, taking Cas’ bag and slinging it over his own shoulder. “It doesn’t matter, Dean you don’t even know me. After my heat I’ll get out of your hair, please let’s just go.” Dean clenches his jaw, growling low in his throat, and Castiel whimpers. 

 

Like a switch flipping, Dean is immediately fussing over Cas, cupping his cheeks between his palms, “I’m sorry, I just… I’m pissed he hurt you. You don’t deserve that.” Castiel turned his head, batting Dean’s hands away, “it doesn’t matter, he’s right. I’m broken.” Cas sighed, closing his eyes, “maybe I should just let him…”

 

Dean sighs, “Cas, look at me.” He waits until he does before continuing. “You aren’t broken, there’s nothing wrong with not wanting to be knotted. You can stay with Sam and me as long as you need, I’m not sending you back to that asshole, alright? Let’s just make it through your heat, then we can worry about everything else.”

 

Cas nods slowly, blinking back tears, “thank you,” Dean shrugs, leading them down the dark street. “I’m not letting anything hurt you, not anymore,” Castiel squeezes his hand, but doesn’t say anything. Something about this alpha is different, Castiel isn’t repulsed, isn’t scared. Dean’s hand feels right in his, they  _ fit.  _

 

He isn’t sure he likes it, he shouldn’t trust this stranger, especially not after he almost killed Balthazar, but… He had only did that because Balthazar had been a threat… He had reacted as if he was protecting his mate. But Cas  _ wasn’t _ his mate, never would be,  _ couldn’t  _ be, there was no use pretending differently. 

 

“This is me,” Dean announced, leading the way up a short stone walkway. Castiel’s jaw dropped at the sight of the small cottage, he had assumed Dean lived in a shitty apartment like him, he hadn’t expected… “There are plenty of extra rooms if you wanna move in, but only mine and Sam’s rooms currently have beds. You can have my room, I’ll crash on the couch tonight and get out of your hair after I introduce you two tomorrow.”

 

Castiel nods, shyly trailing after Dean as he unlocks the door and lets them in. “This is really… yours?” Dean nods, casting a smile over his shoulder at the omega. “Yep, you must be tired, come on, my room’s right down here.” Castiel trailed after him jaw dropping at the sight of the room, “you sure it’s okay if I stay here?” Dean rolled his eyes, “of course. Uhm, do… you have… toys and stuff? For… yanno?” Dean blushed, and Castiel laughed, running a hand through his hair.

 

“Yeah I have… stuff. I’ll be fine, thank you. Really, you have no idea what it means that you’re being so nice to me.” Dean ruffled his hair, smiling down at him, “it’s more than fine. Make yourself comfortable, I’m right down the hall if you need me.”

 

Castiel couldn’t remember a time when he had slept better, for some reason, instead of repulsing him, the scent of  _ this  _ alpha calmed him. He dozed off within minutes of his head hitting the pillow, for once falling into a dreamless sleep, not worrying about Balthazar trying to rape him while he wasn’t conscious. 

 

He doesn’t know Dean, he shouldn’t be so comfortable with him, but the alpha made him feel safe. Dean was stronger than Balthazar, that much was obvious, if he wanted to he could have easily forced Cas into a breeding. He could have killed Balthazar and dragged Cas off, but he didn’t. He stopped when Cas asked him to, he gave Cas the choice to come. He was nothing like a traditional alpha, he seemed to actually  _ respect  _ Cas’ decisions, even though Cas was only an omega.

 

He wondered if Dean felt the same strange comfort at his presence, that could explain why he was willing to let a stranger into his home at least. Although, it didn’t explain the attraction, Cas  _ hated  _ alpha’s, but this one… He didn’t know what to think of him. This was better than being forced to mate though, at least, if Dean did mate him he could probably learn to love him. It wouldn’t he  _ as  _ horrible as being stuck with  _ Balthazar  _ or someone like him. Someone who was willing to - wanted to - rape him.

 

Being stuck with Dean… He... wouldn’t mind it.

 

~!~!~!~

 

The next morning Castiel woke up feeling off, he had thought he had another day or two at least before his heat hit him, but he could already feel himself starting to drift off. He couldn’t exactly remember where he was or what had happened last night, and he was surrounded by the smell of an unfamiliar alpha. 

 

A knock on the door sent him hurtling out of bed and cowering in the corner, he didn’t want this, in another hour he would be throwing himself at whatever alpha was in sight but right now… He was terrified and he  _ didn’t  _ want this.

 

“Cas, it’s Dean. I uh… wanted to introduce you to Sammy before this hits you any harder so can you,” there was a pause before the alpha continued, “come out here?” His voice was strained, he was obviously affected by the pheromones Cas producing, but he could control himself, at least for now.

 

Dean? That hadn’t been a dream? “I’ll… be out in a second.” He called, slowly pulling himself off the floor, digging in his bag for a decent pair of clothes. 

 

When he walked out of the room, Dean was waiting for him, smile glued in place. “Morning Cas, sleep alright?” Dean held out his hand, and Cas nodded, shyly linking their fingers and following him out to the living room. 

  
  


Another omega walked out of the kitchen, balancing three mugs in his hands, “hey, you must be Castiel. I’m Sam, Dean’s brother.” The boy smiled, offering one of the mugs to Cas, and the other to Dean before sipping at his own. “Helps with cramps,” he announced when Castiel cast a questioning look down at the liquid.

 

Castiel smiled gratefully and sipped at the warm drink, “thank you, I uh… I’m not sure what Dean’s told you, and I’m sure, that is I’m sorry, I…” he trailed off, shuffling awkwardly from foot to foot. “Don’t be ridiculous, if Dean  _ didn’t  _ offer to let you stay here I would have killed him. I can’t imagine being forced into a mating, no matter what the reason.” 

 

Dean smiled and wrapped an arm around Castiel’s waist, guiding him to the couch. Sam followed after them and sat down on the sofa across from them, “thank you.” Cas whispered, looking into his cup, blinking back tears that threatened to spill.

 

Dean cast a look at his little brother, and Sam smiled sadly, Cas shouldn’t have had to deal with all that shit. Sure, their biology made it a little less common for asexuality, and it made it a little more difficult, especially for an omega, but it should still be respected. For an alpha to take advantage of his heat.. It was no better than rape. 

 

“Hey, Cas, you’re safe here, okay? I know this entire situation is less than ideal, but we won’t let anything happen to you. I’m not due for another couple days so if you want help with anything don’t hesitate to ask.” Sam soothed, sipping at his tea, and Cas glanced up at him with glassy eyes. 

 

“Thank you, Sam, really. Both of you I can’t…” He sagged against Dean’s side and Sam smiled at the two of them, winking at his brother, who just blushed and looked away. “It’s no problem Cas, now let’s get you back to your room, yeah?” Cas peeked up at Dean, realizing just how affected he was, his pupils blown wide and his fangs extended, still, he smiled kindly and helped Cas to his feet.

 

The omega cast a glance over his shoulder and Sam smiled at him, nodding. Dean took his mug and set both down on the table before leading Cas back to the bedroom. “You have everything you need?” Dean asked and Cas nodded shyly, shifting from foot to foot. “Thank you again, I… We can talk more after, yeah? I’m sorry I really, I don’t know how long I…” Dean smiled fondly, ruffling his hair, “we’ll talk after. Promise.”

 

Cas nodded, retreating into the room. He looked around, this would be his home for the next few days. There was a small fridge, which under closer inspection was full of water bottles and snacks, and there was a lock on the door, which he clicked into place. 

 

Normally he would hate being so enveloped in the sent of an alpha, but Dean’s scent was relaxing. He couldn’t even bring himself to complain as he flopped down on the bed and was surrounded by a new cloud of his strong smell. 

 

Nap, he should nap for now, he didn’t usually get much sleep during his heats, and Dean’s bed was  _ so  _ comfortable. Maybe he could sleep through the first couple hours, that would be good at least. He sighed, closing his eyes, drifting off faster than he expected. 

 

~

 

When he woke up, his thoughts were immediately bombarded with sensation, the smells of his alpha, the soft sheets, too hot against his skin. He had soaked the bed under him in his sleep, and God he  _ wanted.  _

 

He bolted upright, digging through his bag for his fake knot and collapsing back on the bed, not bothering to prep himself before pounding it into himself. Not enough, fuck not  _ near  _ enough. He buried his face in the the sheets, surrounded by the smell of his alpha. Was Dean still here? He sniffed the air, locating him in the kitchen and beaming to himself. 

 

Dean, he needed Dean, he tossed his toy on the bed and bolted out of the room, plastering himself to the alpha and writhing against him, burying his face in his back. “Cas?” Dean choked, turning around, barely resisting the urge to shove the beta over the counter and take.

 

“Need it, please,  _ please  _ knot me alpha,” Cas whined, rocking his aching cock against Dean’s,  _ yees this is what he needed,  _ “please please please.” Dean clenched his fists, shaking his head, “Cas I can’t you don’t… come on, let’s go back to your room.” Cas purred, nuzzling his face into Dean’s neck. 

 

Dean groaned, scooping up the small omega in his arms and carrying him back down the hall, clenching his teeth. Fuck Cas smelled so good and he wanted so fucking bad. He felt the omega’s slick drip down his arm from where he was holding him.

 

“Jesus, Cas, okay, come on,” he panted, tossing the omega on the bed and turning to leave. Cas reached out and snatched the alpha’s arm, dragging him onto the bed, “please Dean, please I need,” he cut himself off, writhing on the sheets. He felt like he was going to explode, “breed me, please, need your knot, mark me,” Cas babbled, rocking against the alpha’s solid body. 

 

Dean groaned, rolling over and pinning the omega down, snarling down at him and rocking his hips against the blissfully hot skin. Cas whimpered, baring his neck to the alpha and clenching his eyes shut, screaming at the feel of sharp fangs tracing over his pulse. 

 

A moment later Dean was growling and shoving Cas away, backing towards the door. Cas whimpered at the loss, trying to get up and follow the alpha, but Dean slammed the door, locking it from the outside. 

 

Cas growled, letting himself fall back on the bed, settling himself writhing on the fake knot and burying his face in the alpha’s pillow, pretending it was Dean plowing into him was enough to have slick dripping down his thighs, a puddle of cum and sweat slowly growing under him. 

 

~!~!~!~

 

Dean sniffed the air, double checking that both Sam and Cas were off their heats before sighing and opening the door, letting himself in. “Hey, Dean,” Sam called from the kitchen, not bothering to stop whatever he was doing. 

 

“Heya Sammy, you seen Cas?” This time, Sam peeked his head out, “dude’s being a recluse, think he’s upset about something but he won’t let me in. Still in your room,” Dean sighed, he figured Cas would be freaking out. “Thanks, I’ll go talk to him.”

 

He dragged his feet down the hall, knocking lightly on the door. “Cas, hey man, let me in. Please.” He sighed, rubbing the back of his neck, when there was no response he sighed, leaning against the wall, “Castiel, come on…” after another minute he heard the lock click, and the door slowly swung open. 

 

“Hello, Dean…” Cas whispered, his voice rough with emotion. “I…can’t tell you how sorry I am, you open your house for me and I…” He trails off, looking down. “I uh, I cleaned up and I’m all packed, I’ll get out of-”

 

“Don’t even think about it, Cas you said yourself you have nowhere to go. Come on, sit,” Dean took Cas’ hand, dragging him into the room and gently pushing him onto the bed. “It wasn’t you, nothing happened, it’s not a big deal.” Dean smiled, squeezing Cas’ small hand, “you don’t have to worry.”

 

Cas finally managed to meet his eyes, feeling his body sag with relief when he realized Dean wasn’t angry. “Still, I…” He shook his head, scooching closer to Dean, “why do I feel safe with you?” He muttered instead, looking shyly up at the alpha, “every other alpha I’ve… ever been around. I was terrified but here…”

 

Dean shrugged, barely catching himself before cupping Cas’ cheek in his palm. “I don’t… I feel the… kiss me.” He finally spit out, hardly able to breath. He had no idea what the  _ hell  _ was wrong with him, he didn’t know Cas, he wasn’t like this, not usually, but…

 

“I don’t know you…” Cas murmured, even as he closed the distance between them. The shock he felt when their lips met definitely clarified a few things, and he jumped back, staring at Dean’s equally shocked eyes. 

 

“I thought…”

 

“Bondmates were made up?” Dean asked, and Cas nodded breathlessly, “same here, but…” Cas nodded again, shyly leaning back up to kiss Dean again, already addicted to the burning heat the connection started in him. 

 

“Well, I guess that settles it, you’re moving in.” Dean announced when they parted, and Cas blushed, looking away. “I still don’t want-” Dean cut him off with another kiss. “I don’t care, we’ll make it work, I promise.” He whispered against Cas’ lips, “you’re mine.” 

**Author's Note:**

> Sammy made me I'm sorry I tried, let me know what you think? <3  
> *whispers* come say hi on tumblr? the-queen-unitato


End file.
